#include<stdio.h>
#include<math.h>
int main () 
{
	double x1,x2,x3,y1,y2,y3,d,e,f,a,b,c,A,m;
	scanf("%d %d %d %d %d %d",&x1,&y1,&x2,&y2,&x3,&y3);
	if(x1==0&&y1==0&&x2==0&&y2==0&&x3==0&&y3==0) break;
	d=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2) ;
	e=(x2-x3)*(x2-x3)+(y2-y3)*(y2-y3) ;
	f=(x1-x3)*(x1-x3)+(y1-y3)*(y1-y3) ;
	a=sqrt(d);
	b=sqrt(e);
	c=sqrt(f); 
	cos(A)=(a*a+c*c-b*b)/2*a*c;
	sin(A)=sqrt(1-cos(A)*cos(A)) ;
	m=0.5*a*c*sin(A) ;
	printf("%d",m);
}
